JPH093041A - Method for producing ε-caprolactam - Google Patents

Abstract

(57) [Summary] [Object] To provide a method for producing ε-caprolactam without producing ammonium sulfate as a by-product. [Structure] ε-caprolactone and / or 6-hydroxycaproic acid ester and ammonia are reacted in the gas phase in the presence of hydrogen and steam using a catalyst composed of copper oxide, molybdenum oxide, chromium oxide and titanium oxide. -Method for producing caprolactam.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing ε-caprolactam from ε-caprolactone and / or 6-hydroxycaproic acid ester and ammonia under a gas phase reaction condition using a solid catalyst. ε-caprolactam is an extremely important chemical raw material that is industrially produced in large quantities as a raw material for polyamide such as nylon 6.

[0002]

2. Description of the Related Art As a current industrial method for producing .epsilon.-caprolactam, a method based on the Beckmann rearrangement reaction of cyclohexanone oxime is generally widely adopted. However, this Beckmann rearrangement reaction has a problem that a large amount of ammonium sulfate is by-produced in a liquid phase reaction using a large amount of a strong acid. On the other hand, various methods have been proposed as a method for producing ε-caprolactam that does not produce ammonium sulfate as a by-product.
Among these, a method of contacting ε-caprolactone with a catalyst in the gas phase in the presence of ammonia has already been proposed.

For example, in Japanese Examined Patent Publication No. 56-10306,
It has been proposed to use a catalyst containing copper, nickel and titanium oxide, but the space-time yield (the amount of ε-caprolactam obtained per unit time per unit amount of catalyst) is not sufficient and it is adopted as an industrial method. It has not been done. Also,
Japanese Patent Publication No. 48-39950 proposes a method in which an amine coexists in the presence of a copper-chromium catalyst in order to improve the space-time yield. However, such a third substance is added to the reaction system. Doing so increases the burden on the purification of ε-caprolactam, which is not industrially preferable.

The space-time yield influences the capacity and cost of the reactor, and further the production cost, and therefore requires as large a value as possible. Generally, to increase space-time yield,
If the amount of raw material treated is increased, the activity and selectivity of the catalyst will be reduced more rapidly, and conversely, economic efficiency will be lost, which is not industrially preferable. Therefore, in order to carry out the production industrially advantageously, it is desired to develop a catalyst having high selectivity, space-time yield, and long-lasting activity.

[0005]

[Means for Solving the Problems]
As a result of earnest research on a method capable of producing ε-caprolactam from a ε-caprolactone and / or 6-hydroxycaproic acid ester which does not have the above-mentioned problems by a gas phase catalytic reaction, a copper compound containing titanium oxide, a molybdenum compound It was found that ε-caprolactam can be produced in high yield over a long period of time by using a catalyst obtained by calcining a mixture precipitated from an aqueous solution of a chromium compound and an aqueous alkaline solution and an alkaline aqueous solution, thus completing the present invention. Came to.

Hereinafter, the present invention will be described in detail. A specific method for preparing the catalyst used in the present invention will be described. First, a required amount of titanium oxide is added to a mixed aqueous solution of a required amount of a copper compound, a molybdenum compound and a chromium compound, and the amount of the mixture is 5-10.
An alkaline aqueous solution is added dropwise at a temperature of 0 ° C. with stirring to adjust the pH to 9 to 13 to obtain a precipitate. The precipitate is thoroughly washed with water and filtered to obtain a mixture of copper compound, molybdenum compound, chromium compound and titanium oxide. This mixture is then added to 100-2
After drying at 00 ℃, mold it into a suitable shape, 400-9
The catalyst is obtained by calcining in N ₂ or air at 00 ° C. for 3 to 15 hours. The catalyst thus prepared is used after being reduced by hydrogen gas after filling the reaction tube and before supplying the raw material gas.

Any commercially available titanium oxide can be used for preparing the catalyst. As the copper and chromium compounds, nitrates, sulfates, formates, etc. can be used,
Nitrate is preferred. Ammonium molybdate is used as the molybdenum compound, but molybdenum oxide powder may be used. Moreover, caustic soda, sodium carbonate, etc. can be used as an alkali used as a pH adjuster. When the composition ratio of copper, molybdenum, chromium and titanium of the catalyst used in the present invention is represented by atomic ratio, C
u: Mo: Cr: Ti = 100: 0.1-50: 0.0
1 to 20:20 to 500, preferably 100: 0.5 to
It is in the range of 20: 0.05 to 10:50 to 300.

As the ε-caprolactone used as a raw material in the present invention, those produced by the oxidation reaction of cyclohexanone with peroxide and other reactions can be used. Examples of 6-hydroxycaproic acid ester include esters of lower saturated aliphatic alcohols having 1 to 4 carbon atoms, and methyl ester is particularly preferable. The amount of ammonia used when carrying out the present invention is
A range of 1 to 30 times mol, preferably 3 to 20 times mol for ε-caprolactone is suitable. The amount of hydrogen is 1 to 60 times mol relative to ε-caprolactone,
The amount is preferably 5 to 50 times, and the amount of water is 1 to 60.
The range of double mole, preferably 5 to 50 mole is suitable.

The reaction temperature is in the range of 200 to 350 ° C, preferably 250 to 330 ° C. The reaction pressure is
1 to 10 kgf / cm ² (gauge pressure), preferably 3 to
A range of 7 kgf / cm ² (gauge pressure) is advantageous. Further, the space velocity when the mixed gas of ε-caprolactone, ammonia, hydrogen and water is brought into contact with the catalyst is 10
0 to 10,000 hr ^-1 , especially 300 to 7,000 hr
A range of ^-1 is preferred.

The ε-caprolactam can be separated from the reaction product obtained by cooling and condensing the gas after the reaction by operations such as distillation and extraction. Most of the non-condensable gas consists of ammonia and hydrogen, which are recycled to the reaction system for reuse. Further, the catalyst whose activity has decreased due to long-term use can be regenerated by firing in an oxygen-containing gas and can be used repeatedly.

The present invention will be specifically described below with reference to examples. In the examples, reaction results were defined by the following formula.

[0012]

【Example】

Example 1 Cupric nitrate trihydrate 200 g, chromium nitrate nonahydrate 0.33
g and 2.92 g of ammonium molybdate were dissolved in 3 l of pure water, and 66.1 g of titanium oxide powder (Ishihara Sangyo W-10) commercially available, which was calcined at 800 ° C for 5 hours in air, was added while stirring at room temperature. It was While continuing stirring, a 15 wt% caustic soda aqueous solution was slowly dropped, and when the pH of the solution reached 12.0, the dropping was stopped, and stirring was continued for another hour to obtain a precipitate. The precipitate was washed with water, filtered, and dried at 120 ° C. for 16 hours. The dried precipitate was pulverized to a powder having a particle size of 500 μm or less, and graphite corresponding to 3 to 5% by weight of the weight of the precipitated powder was added, and the mixture was tableted into pellets of 3 × 3 mm. The obtained molded product was baked in air at 400 ° C. for 5 hours. The composition of the catalyst after calcination is Cu: Mo: Cr: Ti = 100:
It was 2: 0.1: 150 (atomic ratio). Main catalyst 40m
1 was charged into a stainless steel reaction tube, and 3.5
Reduction was performed with a volume% hydrogen (in N ₂ ) gas overnight. afterwards,
The reaction system was replaced with nitrogen gas, and the pressure inside the system was set to 5 kgf / c.
The pressure was adjusted to m ² (gauge pressure). ε-caprolactone: ammonia: hydrogen: water = 1: 10: 20: 30 (molar ratio)
280 at a speed of SV = 2,900 hr ⁻¹
After supplying to the catalyst layer kept at ℃,
Continued for hours. For a certain period of time, the product is cooled and collected,
The results of gas chromatograph analysis of the collected liquid are shown in Table 1 together with Comparative Examples 1 to 3.

Comparative Example 1 In the same manner as in Example 1, from copper nitrate and titanium oxide to C
A catalyst having u: Ti = 100: 150 (atomic ratio) was prepared. The results of carrying out the reaction at 300 ° C. in the same manner as in Example 1 are shown in Table 1.

Comparative Example 2 In the same manner as in Example 1, Cu: Mo: Cr = 100:
A catalyst not containing titanium oxide of 2: 0.1 (atomic ratio) was prepared and reacted at 280 ° C. in the same manner as in Example 1,
The results are shown in Table 1.

Comparative Example 3 Commercially available Adkins-type catalyst (NGC 201: N-201) 40
The reaction tube was filled with ml, and the reaction was carried out at 300 ° C. in the same manner as in Example 1. The results are shown in Table 1.

Example 2 As in Example 1, Cu: Mo: Cr: Ti = 100:
A catalyst of 5: 0.1: 150 (atomic ratio) was prepared. SV = 3,800 hr ^-1
The reaction was carried out at 300 ° C. in the same manner as in Example 1 except that The results are shown in Table 2.

Example 3 As in Example 1, Cu: Mo: Cr: Ti = 10.
A catalyst of 0: 2: 0.1: 150 (atomic ratio) was prepared. The reaction was carried out at 280 ° C. in the same manner as in Example 1 except that methyl 6-hydroxycaproate was used as a raw material instead of ε-caprolactone. The results are shown in Table 3 in comparison with the results of Example 1.

Example 4 Instead of the titanium oxide powder W-10 used in Example 1,
Using a product obtained by firing MC-50 (Ishihara Sangyo) in air at 600 ° C. for 5 hours, a 3 × 3 mm tablet-molded article was obtained in the same manner as in Example 1. The obtained molded product is heated to 700 ° C in air.
It was baked for 7 hours. The catalyst composition after firing was Cu: Mo:
Cr: Ti = 100: 2: 0.2: 100 (atomic ratio). Then, after carrying out catalytic reduction in the same manner as in Example 1, the reaction was carried out at 300 ° C. in the same manner as in Example 1. The reaction was continued for 3 days, and the results are shown in Table 4.

Example 5 As in Example 4, catalyst preparation was carried out using titanium oxide powder MC-50 which was calcined in air at 600 ° C. for 5 hours.
A molded product of × 3 mm was obtained. This molded product in N ₂ at 700 ° C.
Calcination for 7 hours, catalyst composition Cu: Mo: Cr: Ti = 1
A catalyst of 00: 3: 0.2: 100 (atomic ratio) was obtained. The results of carrying out the reaction at 300 ° C. in the same manner as in Example 1 using this catalyst are shown in Table 5.

Example 6 In the same manner as in Example 4, Cu: Mo: Cr: Ti = 10.
A catalyst of 0: 3: 0.1: 100 (atomic ratio) was prepared.
Using this catalyst, the reaction was carried out at 300 ° C. as in the case of Example 1. After the reaction was continued for 250 hours, the catalyst was regenerated by calcination with 2% O ₂ gas (in N ₂ ) and air, and the reaction was further repeated for 250 hours to carry out continuous operation for about 1 month. Table 6 shows the results.

[0021]

[Table 1]

[0022]

[Table 2] Table 2 Reaction temperature [℃] 300 300 300 300 Reaction time [hrs] 4 24 48 72 Lactone conversion rate [%] 100 99.8 99.6 99.0 Lactam selectivity [mol%] 70.6 76.6 82.4 82.1 Lactam yield [mol] %] 70.6 76.4 82.1 81.3 Space-time yield [g / l. hr] 222 240 258 255

[0023]

[Table 3] Table 3 Raw materials ε-caprolactone methyl ester ────────────────────────────── Reaction temperature [℃] 280 280 280 280 Reaction time [hrs] 4 24 4 24 Lactone conversion [%] 100 99.6 99.5 99.0 Lactam selectivity [mol%] 80.3 83.4 82.1 83.7 Lactam yield [mol%] 80.3 83.1 81.7 82.9 Space time yield [g / l ． hr] 193 199 196 199

[0024]

[Table 4] Table 4 Reaction temperature [℃] 300 300 300 300 Reaction time [hrs] 4 24 48 72 Lactone conversion [%] 100 99.9 99.8 99.6 Lactam selectivity [mol%] 81.9 85.0 85.5 86.1 Lactam yield [mol] %] 81.9 84.9 85.3 85.8 Space-time yield [g / l. hr] 196 204 205 206

[0025]

[Table 5] Table 5 Reaction temperature [℃] 300 300 300 300 Reaction time [hrs] 4 24 48 72 Lactone conversion rate [%] 99.9 99.5 99.2 98.7 Lactam selectivity [mol%] 83.2 87.5 88.5 86.1 Lactam yield [mol] %] 83.1 87.1 87.8 85.0 Space-time yield [g / l. hr] 199 209 211 204

[0026]

[Table 6] Table 6 First reaction time [hrs] 4 48 123 170 220 Lactone conversion [%] 100 99.9 99.8 99.6 99.1 Lactam selectivity [mol%] 80.7 85.5 84.6 83.4 83.6 Lactam yield [mol%] 80.7 85.4 84.4 83.1 82.8 Space-time yield [g / l. hr] 194 205 202 199 199 Second time (after catalyst regeneration) Reaction time [hrs] 255 302 373 398 446 Lactone conversion [%] 100 100 99.7 99.7 99.3 Lactam selectivity [mol%] 79.8 83.8 84.0 84.6 84.7 Lactam yield [Mol%] 79.8 83.8 83.7 84.3 84.1 Space-time yield [g / l. hr] 191 201 201 202 202 3rd time (after catalyst regeneration) Reaction time [hrs] 525 597 645 703 746 Lactone conversion [%] 99.9 99.8 99.6 99.5 99.1 Lactam selectivity [mol%] 79.5 83.0 83.7 84.0 83.5 Lactam yield [Mol%] 79.4 82.8 83.4 83.6 82.7 Space-time yield [g / l. hr] 190 199 200 200 198

[0027]

INDUSTRIAL APPLICABILITY The catalyst used in the present invention has a high space-time yield as compared with conventional catalysts, and since the catalyst activity is maintained for a long time, it is industrially applicable. Therefore, this method has great industrial significance as a method for producing ε-caprolactam without ammonium sulfate by-product.

Claims (3)

[Claims] 1. Epsilon-caprolactone and / or 6-
A process for producing ε-caprolactam, which comprises reacting a hydroxycaproic acid ester and ammonia in the gas phase in the presence of hydrogen and water vapor using a catalyst composed of copper oxide, molybdenum oxide, chromium oxide and titanium oxide. 2. The method according to claim 1, wherein a catalyst obtained by adding an alkaline aqueous solution to an aqueous solution of a copper compound containing titanium oxide, a molybdenum compound and a chromium compound and calcining the deposited mixture is used. . 3. The reaction pressure is a gauge pressure of 1 to 10 kg / c.
Method according to claim 1, characterized in that it is carried out in the range m ² .